Glow discharge tube circuit



June 11, 1935. F. scHROTER 2,004,537

GLOW DISCHARGE TUBE CIRCUIT Filed April 19,- 1950 Jm/en for 17-172 5chr6 fer- F/ I W W UNITED STATES PATENT OFFICE GLOW DISCHARGE TUBE CIRCUIT Fritz Schr6ter, Berlin-Schmargendorf, Germany, assignor to Radio Patents Corporation, New York, N. Y.

Application April 19, 1930, Serial No. 445,790

. In Germany July 11, 1929 10 Claims. (01. 178-7) This invention relates to a glow discharge tube which are transmitted in the form of modulated filled with rare gases or mixtures of rare gases at alternating current, more especially when the frelow pressures, which tube can be traversed by quency of the said current is modulated. In this electric alternating current voltages beyond cercase the property of the arrangement with an tain values producing ionization and illumination, outer electrode of automatically preventing a con- 5 whilst it does not allow a continuous current to tinuous current to pass through is an advantage, pass through. Such a tube supplies a discharge as it is no longer necessary to prevent the contincurrent which is not dependent only upon the uous current component of the signal from reachvalue of the applied alternating current voltage ing the circuit-of the tube.

'but also upon the frequency thereof, so that the lath case just referred to, it is preferable to 10 strength of the current or the brightness of the make the tube according to Figure 2 very narlight which is emitted is a measure for the amrow and to observe the discharge through a winplitude and the frequency of the said voltage. do'w't inthe longitudinal direction of the tube,

I The effective current passing through a condenser or to allow the discharge to act through the said 5 with a capacity C is i=:C.w.E, wherein'E is the, window. In this way a We lfi P011113 0f effective alternating current voltage and w the light of great brightness is obtained. The inner periodicity of the cycle. If the discharge tube acelectrode is in this case constructed as a hollow cording to the present invention is constructed cathode containing a store of strongly electroas shown in Figure 1, wherein one electrode is in positive metal, for instance potassium, sodium,

the interior of the vessel whilst thesecond eleccasium, barium or magnesium, or which it can 20 I trode forms the condenser armature on the outdevelop from a suitable reaction mixture under side of the vessel, a glow discharge flows through the'influence of the heat due to the discharge. the gas, the effective current E and w of which are The vapours of these metals keep the gas filling proportional, that is to say it increases and depure and therefore the electric properties of creases at constant voltage with the frequency the tube remain constant. 25

and at constant frequency with the voltage. Referring to the accompanying drawing,

If a travelling wave with an inclined front acts Fi 1 and 2 how construc ions of tubes upon such a tube, the starting displacement curwhich can be used according to the invention.

rent andtherewith the brightness of the tube mo- Figure 3 is a diagram of connections of a regmentarily emitted, is proportional to the inclinaistering device used in power lines, and 30 tion of the wave, thus the observation or register- Figure 4 is a diagram of connections used with ing of the illumination can serve for arriving at a picture transmission according to the invention. conclusion as regards the value and the inclina- Referring to Figures 1 and 2, I is a glass,

tion of the excess voltage. As the brightness can quartz, or liketube, 2 is an inner electrode and be continuously registered on a movable photo'- 3 an outer electrode. In the form of construc- 35 graphic surface, the form and the strengthof tion shown in Figure 2, there is also arranged voltage waves in conducting systems with which insidethe tube a separate narrow part 5, which the tube is connected directly by a capacity or can be seen from the front end 4 of the tube, through an inductance, can be continuously suthe said part 5 being preferably made of the 40 pervised by such photograms. same material as the tube, viz, glass, quartz, or 40 The construction according to Figure 2 makes it the like, through which the glowing displacepossible to obtain a sharp and well defined spotment current can pass and thus be concentrated like luminous source which may be disposed close so that the light effect through the window 4 against the window 4, thus making it possible to can be increased. dispense with special collecting lenses and there- In the diagram illustrated in Figure 3, 8 is a 45 by decreasing the cost of the equipment. Furportion or branch of a power installation also thermore, a tube of the type shown embodying an containing overhead lines, on which therefore external electrode, and a narrow channel 5 for electric charges are accumulated, which are producing a sharp spot-like light source enables propagated in the form of waves. In the part the arrangement of an extended electrode 3 on 8 a separate branch 'I is inserted which may, for 50 the outside wall. of the main vessel l with a corinstance, consist of a choking coil or any other responding large capacity surface resulting in a member producing a potential difference at its decrease of the effective impedance of the gap. two ends. The glow tube l according to the in- Moreover, the tube according to the invention vention is connected to the two sides of the said 5 may beused for observing or registering signals branch 1 in such a manner that the inner elec- 55" trode 2 lies on the one side and the outer electrode 3 on the other side of the branch I. 6 is a resistance for limiting the strength of the current in the glow tube. If a travelling wave strikes on the branch I owing to the suitable dimensions of the latter, a sufficient potential difference is produced at its two ends in order to light up the tube I. The light which passes through at 4 is projected, preferably after passing through a condensing lens 9, on a light-sensitive strip it at a point at which the latter is uncovered by the light-protecting cover 13. .The light sensitive strip is fed in the direction of the arrow into the container H in which it can be developed and fixed so that when it comes out at l2 into the open, it shows darkened points which correspond to the voltage reaching the tube and which give an indication of the inclination of the travelling wave.

In the diagrammatic example illustrated in Figure a picture transmission with frequency modulation is shown. Let white correspond to the frequency an and black to the frequency 102. Then the tones between black and white are transmitted by frequencies which are different from one another. Let these frequencies be transmitted over the lines 15, ldw'hich may be con,- nected .to an aerial or a wire line and reach the amplifier I8 over the transformer H, from which amplifier they pass to the grid circuit of the rectifying tube 22. The said grid circuit also con-- tains the grid bias battery 23 and the transformer i9, 28 to the terminals 2| of which a local oscillator (not shown) having a constant frequency we is connected. is a source of current for heating the filament and 25 an anode battery for the rectifier 22. Owing to the superposition and rectification, the frequency wi minus we will operate in the anode circuit of the rectifier when white is transmitted, Whilst the frequency w2-w0 operates therein when black is transmitted. Let us assume that the frequency differences are as follows (when 201 is ,6500 cycles, 202:2,090 periods, and :1,500 cycles:

wz-wo:500 cycles w1w0=5000 cycles These frequency differences are transmitted over the transformer 26to the glow tube l, which in the case of lower frequency glows less than in the case of higher frequency, so that the tones between white and black are reproduced by the different degrees of brightness of the tube and therefore can be reproduced photographically. The light which passes through the window 4 of the tube and is collected by the lens I4, is projected in the form of a spot of light on the drum 2! on which the film or photographic paper is mounted.

The frequencies w1-{-wo and w2+wo which are produced by heterodyning are kept away from the glow tube, preferably by filter circuits (not shown) in the output circuit of the rectifying tube or input circuit of the glow tube.

It is to be understood that the drum 2'! must run in the direction of the, arrow 28 at the same speed as the transmitting drum at the trans,- mitting end, on which transmitting drum the picture (or facsimile) to be transmitted is mount: ed. In the same way the drum 2'! must be moved axially in the direction of the arrow 29 at the same speed as the transmitting drum at the transmitting end.

What I claim isr 1. In a signalling system a receiving circuit; means for transforming signals of constant amplitude and variable frequency into signals of variable amplitude consisting'of a glow discharge tube, a first electrode within said tube, a second electrode on the outside of said tube; said electrodes forming a condenser therebetween, and means for impressing signals from said receiving circuit, across said electrodes, of constant current amplitude and variable frequency.

'2. In a picture transmitting system; means for transmitting picture signals of constant current amplitude and varying in frequency in accordance with the light and shades of a picture, a receiver comprising means for transforming constant amplitude variable frequency signals into signals of variable amplitude consisting of a glow discharge tube having an internal electrode and an external electrode directly inserted in said re ceiver to be controlled by said variable frequency signals.

3, In combination with a signal receiving circuit of means for translating signals of constant amplitude and varying frequency into corresponding signals of varying amplitude consisting of a glow discharge tube having an external and an internal electrode directly inserted in said.

circuit, and means for utilizing light variations of said. tube in accordance with said varying frequency;

4. In combination with a signal receiving cir-' cult of means for translating signals of constant amplitude and varying frequency into corresponding signals of varying amplitude consist-' ing of a glow discharge device, an internal and external electrode of said device, means for applying input signalsto said electrodes, and means derivingoutput signals in accordance with light variations of said' tube produced by said input signals.

5. In combination with a signalling system, a receiving circuit; means for transforming constant amplitude variable frequency signals into corresponding variable amplitude signals comprising a glow discharge device consisting of a vessel of insulating material filled with a gaseous atmosphere, a narrow tube within said vessel having one end connected to said vessel and having' its other end open to divide said vessel into two communicating chambers; a first electrode within said vessel; a second electrode on the outside wall of said vessel, said electrodes forming an electrical condenser with said vessel acting as a dielectric and said gas as a current conductor; means for impressing signals from said receiving circuit across said electrodes; and further means for utilizing light variations within said tube in accordancewith the signals applied to said electrode.

6. In a signal receiving device; as claimed in claim 5, provided with a window, the open end of said tube being disposed close against said window.

7. In combination with a signalling system, a

receiving circuit; means for transforming conbers; a first electrode within said vessel; a second electrode on the outside wall of said vessel, said electrodes forming an electrical condenser with said vessel acting as a dielectric and said gas as a conductor; means for impressing signals from said receiving circuit across said electrodes and further means for utilizing light variations within said tube in accordance with signals applied to said electrodes.

8. In a signal receiving device as claimed in claim 7 in which said discharge vessel is provided with a window, the open end of the tube being arranged close against said window.

9. In combination with a signalling system, a circuit for receiving signalling currents; means for translating said currents comprising a glow discharge device consisting of a vessel of insur lating material filled with a gaseous atmosphere;

a narrow tube disposed within said vessel having one end connected to said vessel and having its other end open to divide said vessel into two communicating chambers; a first electrode within said vessel; a second electrode on the outside wall of said vessel, said electrodes forming an electrical condenser with said vessel acting as a dielectric and the gas as a current conductor; means for applying signalling currents to said electrodes; a window for said vessel, the open end of said tube being arranged close against said window; and further means for utilizing light variations within said tube in accordance with the signals applied.

10. In combination with a signalling system, a circuit for receiving signalling currents; means for translating said currents comprising a glow discharge device consisting of a vessel of insulating material of substantially cylindrical shape filled with a gaseous atmosphere; a narrow concentric tube of insulating material within said vessel having one end connected to and integral with said vessel and having its other end open to divide said vessel into two communicating chambers; a first electrode within said vessel; a second electrode on the outside wall of said vessel, said electrodes forming an electrical condenser with said vessel acting as a dielectric and the gas as a current conductor; means for applying signal ling currents to said electrodes; a window for said vessel, the open end of said tube being arranged close against said window; and further means for utilizing light variations within said tube.

FRITZ scHRoTER. 

